I build my replica's around 1990. If memory serves me right. It had the HIF13 in both mid and low. I believe the commercial model already had the 17cm. woofer by then. The guy I bought my speaker stuff from back then (Audio Dome in Amsterdam) tried to find the crossover values for the 17cm, but I sold the speakers before he ever found out.
So I don't know what model I copied, but it was definitely one of the older versions.

The 2606 had similar character in the mids and lows compared to the 1303. Only with lower bass extention and a bit less critical for amplifiers. But it would be complicated to reproduce. I don't have a clue anymore about the exact tuning of the Helmholtz resonators on the HM130G0.

Nuttyhifi is right it is easier and cheaper to buy a used one. Although in most cases the HIF13 will probably be in bad shape. In any case I would avoid the polyester ones (they all dtart to resonate at some point) and the Foster tweeter (I don't like that sound).

And about Elipson vs Duson: this is much more about 1303 (and derivates) vs other Elipsons as well. This speaker really was a very special one. And the Libre, Isis and Orphee were Elipson designs that were manufactured under license.
The 2202 was a Studio de Schop design turned 90 degrees. And the old Colonne Duson (with 2x audax 17cm) was designed by Elipson, exclusively for Duson.